Train Traces News Today

>> the fbi and nypd have launched an investigation into a pair of letters that tested positive for the poison ricin. one of sent to new york michael bloomberg, the other to the director of his gun control group. nbcs tracie potts joins us live from washington now with more on the investigation. good morning. >> reporter: what we know this morning, mara s that those letters were intercepted before anyone was hurt, and that earlier tests confirm they did con train traces of the deadly poison ricin...